In recent years, sensor technologies and video processing technologies have been improved so that they are used in various sport fields. For example, with regard to team sports, such as soccer, basketball, or volleyball, there are conventional technologies for tracking the movement of the players or the ball during a game by using sensor technologies or video processing technologies. An explanation is given below of conventional technologies 1 and 2 as examples.
According to the conventional technology 1, the court where players are playing is captured by multiple cameras, and the ball is detected through image processing, such as matching. Furthermore, with the conventional technology 1, the position of the ball is calculated on the principle of stereo images. Furthermore, with the conventional technology 1, the players are detected through image processing as is the case with the ball, whereby the positions of the players may be also calculated on the principle of stereo images.
According to the conventional technology 2, a sensor is attached to the ball, and a communication is performed with the attached sensor so that the position of the ball is calculated. If a sensor is also attached to a player, the position of the player may be also calculated.
Some of the conventional technologies use the above-described conventional technologies 1, 2, or the like, to conduct tracking by repeatedly performing a process to calculate the position of the ball or the player and then present the tracking result of the ball or the player. FIG. 20 is a diagram that illustrates an example of the tracking result according to a conventional technology. In the example illustrated in FIG. 20, the two-dimensional positions of the players in the first team, who is present in a court 1, and the two-dimensional positions of the players in the second team are displayed in an identifiable manner.
Furthermore, aside from the tracking result illustrated in FIG. 20, the video data, captured by each camera, is stored in the database and, after the game is finished, the player searches for the video at the time of a shot and checks one's form during the shot.    [Patent Literature 1] Japanese National Publication of International Patent Application No. 2014-531588    [Patent Literature 2] Japanese Laid-open Patent Publication No. 2003-174609    [Patent Literature 3] Japanese Registered Utility Model No. 3012003    [Patent Literature 4] Japanese Laid-open Patent Publication No. 3-139374
However, the above-described conventional technologies have a problem in that it is difficult to search for the image desired by a user in an effective manner.
The above-described conventional technologies 1 and 2 are to detect the positions of the players or the ball, but not to detect the specific video data desired by users. Therefore, if a user is to check one's form at the time of a shot, it is typical that the user checks the video data stored in the database so as to identify the video data in the period of time during which the user makes the shot, which results in high workloads on users.
Furthermore, if the conventional technology 1 is used to identify the video data at the time of a shot through image processing, the processing loads become high and the accuracy is decreased, as there are various patterns, such as a case where there are multiple players on the same image, or a case where multiple players have different balls during practice. Moreover, according to the conventional technology 2, even if there are multiple players, the position of the ball may be detected; however, as the special ball, including the sensor, is used, it is difficult to use it during an official game.